Rotatable valve assembly

ABSTRACT

Rotatable valve assembly includes a mounting mechanism for rotatably mounting a valve in a housing. The mounting mechanism includes a shaft having an outside end extending through the housing. A conversion mechanism converts fluid pressure in the housing into torque exerted on the shaft. A release mechanism is located outside the housing for preventing rotation of the shaft and valve when the torque exerted on the shaft is below a selected magnitude. A linearizing mechanism converts the forces exerted on the release mechanism by the shaft into a linear force. The release mechanism allows the shaft to rotate when the torque exerted on the shaft and the linear force exerted on the release mechanism exceeds a selected magnitude. A seal is provided for sealing the gap between the valve and the housing in the closed position of the valve. The seal includes a support edge sealingly secured to the housing, a sealing edge extending inwardly from the support edge into contact with the valve circumference in the closed position of the valve, and a seal body connected between the support edge and the sealing edge and spacing the sealing edge axially towards the inlet face of the valve from the support edge.

This is a divisional application of Ser. No. 08/706,174 filed Aug. 30,1996, now U.S. Pat. No. 5,947,445.

BACKGROUND OF THE INVENTION

The present invention relates to rotatable valve assemblies and moreparticularly, but not by way of limitation, to a rotatable valveassembly which may be used as a pressure relieving device.

The use of various sorts of rupture disks and pressure relief valves toprevent overpressure of a fluid pressure containment structure areknown. For example, U.S. Pat. No. 3,472,284 (Hosek) discloses a pressureseal in which disks 26, 32 rotate about offset shaft 24. A diaphragm 14is clamped between the disks and housing to seal the assembly and thediaphragm is sheared by the rotation of the disks when a desired fluidpressure is present. In order to reseal the valve, the housing members10, 12 must be opened and the valve taken out of service.

U.S. Pat. No. 3,039,482 (Goldberg) discloses a butterfly-type valve inwhich the longitudinal axis of the inlet and the longitudinal axis ofthe outlet are offset so that when the valve is forcibly oscillated andthe hermetic sealing sheet 13 is sheared, the sealing ring 18 on thelower edge of the valve 16 will safely clear the rough and sharp shearededge of sheet 13. The inlet and outlet body sections 11, 12 must betaken out of service and opened in order to reseal the valve after apressure relieving event.

U.S. Pat. No. 2,304,491 (Allen) and U.S. Pat. No. 3,603,333 (Anderson)disclose traditional right-angle relief valves in which a shear pin isused to hold the valve in a closed, sealed position until a preselectedpressure is experienced in the inlet to the valve. Upon overpressure,the valve shears the shear pin and is moved to an open, pressurerelieving position. Since both of these valves use a shear pin, thetolerances between the member holding the shear pin stationary and themoving member which shears the shear pin are critical to provide apredictable relief pressure. For example, referring to the Allen patent,the diameter of the stem 8 and the internal diameter of the bushing 9through which the pin 13 passes must be carefully matched to achieve anaccurately predictable shear pressure. As the space or gap between thesides of the stem 8 and the internal diameter of the bushing 9increases, the force required to shear the pin 13 diminishes rapidly.This requires precision machining and matching of the componentry thatis difficult and expensive to repeatably produce and to maintain. Othershortcomings of the right-angle relief valves include the increased bodysize and the flow restriction created by the right angle turn in theflow passageway, as well as the tendency of the valve to flutter orchatter on the seat during pressure fluctuations because the valve mustresist the entire fluid pressure exerted at the inlet, i.e., the shearpin and spring must directly resist the full force exerted on the faceof the valve by the inlet pressure and directly absorb all pressurefluctuations.

U.S. Pat. Nos. 4,724,857, 4,787,409, 4,930,536, 4,977,918, 5,012,834,5,067,511, 5,116,089, 5,146,942, 5,209,253, 5,226,442, 5,273,065,5,297,575, 5,311,898, 5,318,060, 5,348,039, 5,373,864, and 5,433,239,all issued to Taylor, disclose pressure relief valves, emergency shutoffvalves, vacuum/pressure release valves, and shutoff valves, which use arupture or buckling pin which directly resists the substantially axialmotion of a valve. The Taylor patents do not disclose the use of arupture pin with a rotatable valve assembly, such as a butterfly valve,ball valve, plug valve, or the like; the use of a rupture pin which isnot directly aligned with the motion of the valve; the use of a releasemeans which increases the leverage the valve has on the buckling pin; orthe use of a linearizing means to align the force the valve exerts withthe axis of the buckling pin.

It is known to use rupture disks, such as reverse buckling rupturedisks, to replace right-angle relief valves. Rupture disks have a lowercost per unit of capacity when compared to right-angle relief valves.However, rupture disks must be taken out of service to restore theirpressure containing capability after a pressure relieving rupture. Thisrequires either a redundancy (the use of multiple rupture disks inparallel), shutting down the system, or risking exposing the system tooverpressure while the rupture disk is being replaced.

It is known to use rotatable valve assemblies, such as butterfly valves,ball valves, plug valves, and the like, to control or relieve fluidpressure in fluid containment systems. However, the prior rotatablevalve assemblies known to the applicants typically require that thevalve disk, ball, or plug, wipe or drag across a high friction, tightfitting seal made of elastomer or Teflon®; or use a seal which makes a"face" contact of substantial surface area around the valve. Therefore,a relatively high torque is required to open the prior valve assemblies,and this torque increases with time while the valve is in a closedposition.

For example, Watts Regulator Company manufactures a Series QFQuarterflex butterfly valve which discloses a pressure assisted seatdesign. The line pressure exerts an upward force on the seat whichforces the seat against the valve disk "accordion" style. The sealingsurface of the seal is substantially in diametrical alignment with theseal seat which connects the seat to the retainer, i.e., there is adouble fold in the seal which substantially aligns the seal seat and thesealing surface such that the sealing surface is not axially displacedfrom the seal seat. The sealing surface has a face of substantial axialdimension which creates a face seal of substantial surface area aroundthe circumference of the disk. Such a face seal exerts substantiallygreater friction, requiring substantially greater torque to open andclose, than the point or edge-type seal of the present invention. Watts'valve also uses a double offset shaft to reduce seat wear and enhancesealing by providing a camming action that is disclosed as lifting thedisk off the seat.

U.S. patent application Ser. No. 08/519,653, which is assigned to theassignee of the present application, and which is incorporated herein byreference for purposes of disclosure, discloses a rotatable valveassembly which includes a seal which folds or bends about its rotationalaxis as the valve rotates from the closed to the open position. The sealhas an endless protuberance which extends into a notch formed betweenthe valve and housing in the closed position of the valve. Although thefolding seal is a great improvement over prior devices, it requiresbetween eight and thirteen foot pounds of torque to move theprotuberance into and out of the notch as the valve closes and opens.The improved seal of the present invention reduces the torque requiredto open and close the valve to between one and three foot pounds.

There is a need for a valve assembly which will provide fluid pressurerelief at an accurately predictable relief pressure and which may bereturned to its pressure containing state after a pressure relievingevent without taking the assembly out of service. There is also a needfor a rotatable valve assembly which will reduce the frictional forceswhich must be overcome to rotate the valve between the open and closedposition and in which the torque required to initiate rotation of thevalve does not increase as the valve is left in a closed position forextended periods of time.

SUMMARY OF THE INVENTION

The present invention is contemplated to overcome the foregoingdeficiencies and meet the above-described needs. In accomplishing this,the present invention provides a novel and improved rotatable valveassembly.

The invention is a rotatable valve assembly which includes a housinghaving an inlet and an outlet defining a fluid passageway through thehousing; a valve located in the passageway which is rotatable between aclosed position and an open position; mounting means for rotatablymounting the valve in the housing, the mounting means having a shaftwith an outside end extending through the housing which is rotatablewith the valve; conversion means for converting fluid pressure in thehousing into torque exerted on the shaft; and release means locatedoutside the housing for preventing rotation of the shaft and valve whenthe torque exerted on the shaft is below a selected magnitude and forreleasing the shaft in order to allow rotation of the shaft and valve tothe open position when the torque exerted on the shaft exceeds aselected magnitude. Linearizing means is provided for converting theforces exerted on the release means by the shaft into a linear force.

Preferably, the release means is a deformable means extending betweenthe shaft and housing in order to prevent rotation of the shaft, thedeformable means deforming or rupturing to allow rotation of the shaftand valve to the open position when the torque exerted on the shaftexceeds a selected magnitude. The deformable means may be a pin, beam,wire, or spring which ruptures, bends, buckles, or otherwise deforms toallow rotation of the shaft and valve. In another embodiment, therelease means is a magnetic catch which prevents rotation of the shaftuntil the torque exerted on the shaft exceeds a selected magnitude.

A seal is provided for sealing the gap or space between the valvecircumference and the fluid passageway in the closed position of thevalve. The seal includes a support edge sealingly secured to the fluidpassageway, a sealing edge extending inwardly from the support edge intocontact with the valve circumference in the closed position of thevalve, and a seal body connected between the support edge and thesealing edge and displacing the sealing edge axially towards the inletface of the valve from the support edge. The preferred sealing edgemakes a point contact or line contact of minimal axial dimension andminimal surface area around the valve circumference in the closedposition of the valve in order to reduce the frictional forces exertedon the valve by the seal.

In a preferred embodiment, the rotational axis of the valve defines afirst portion of the seal and sealing edge and a first portion of thevalve and valve circumference on one side of the rotational axis, and asecond portion of the seal and sealing edge and a second portion of thevalve and valve circumference on the other side of the rotational axis.The first portion of the valve rotates into the outlet of the housingwhen the valve rotates from the closed to the open position. The axialdimension of the valve circumference in contact with the sealing edge inthe closed position of the valve is constructed and arranged so that thefirst portion of the sealing edge breaks contact with the first portionof the valve circumference simultaneously with the second portion of thesealing edge breaking contact with the second portion of the valvecircumference as the valve rotates from the closed position to the openposition. The improved seal may be used independently of the features ofthe valve and independently of the conversion means and release means invirtually any rotatable valve assembly.

It is an advantage of the present invention to provide a rotatable valveassembly which will open at a predictable and repeatable torquemagnitude, regardless of the length of time the valve has been in theclosed position.

It is an advantage of the present invention to provide a seal for arotatable valve assembly which allows the valve assembly to be opened ata predictable and repeatable torque magnitude.

It is an advantage of the present invention to provide a pressurerelieving rotatable valve assembly which may be reset or restored to apressure-containing condition without opening the assembly or taking theassembly out of service.

It is an advantage of the present invention to provide a pressurerelieving rotatable valve assembly which will automatically reset to apressure-containing condition without opening the assembly or taking theassembly out of service.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly which reduces the forces the valvemust resist and transmit to remain closed.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly which will replace traditional reliefvalves at a substantial cost savings and using a smaller valve housing.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly in which a large diameter butterflyvalve may be used in relatively high pressure applications and using arelatively small rupture pin or magnetic catch to determine the pressureat which the butterfly valve will open.

It is an advantage of the present invention to provide such an assemblywhich improves the ability of the rotatable valve to be repeatedly resetto the same relieving pressure.

It is an advantage of the present invention to provide such an assemblywhich allows the valve to be repeatably reset without replacement parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by reference to theexample of the following drawings:

FIG. 1 is a view along line 1--1 of FIG. 3.

FIG. 2 is a schematic end view of an embodiment of the invention.

FIG. 3 is schematic end view of an embodiment of the invention.

FIG. 4 is schematic left side view of an embodiment of the release meansof FIG. 2.

FIG. 5 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 6 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 7 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 8 is an elevational end view of the outlet of a rotatable valveassembly of the present invention.

FIG. 9 is a view along line 9--9 of FIG. 8 reoriented 180°.

FIG. 10 is an enlarged detailed view of a portion of the seal with thevalve in the closed position, as indicated on FIG. 9.

FIG. 11 is a cross-sectional view of the seal shown in FIG. 10.

FIG. 12 is a cross-sectional view of another embodiment of the sealshown in FIG. 10.

FIG. 13 is a replication of FIG. 10 used for additional description andexplanation of the invention.

FIG. 14 is a view of FIG. .9 showing the valve just before the sealbreaks contact with the valve.

FIG. 15 is a view of FIG. 9 showing the valve in the fully openedposition.

FIG. 16 is a schematic side view of an embodiment of the reclosure meansof the invention.

FIG. 17 is a schematic side view of another embodiment of the reclosuremeans of the present invention.

FIG. 18 is a schematic side view of another embodiment of the reclosuremeans of the present invention.

FIG. 19 is a plan view of the reclosure means of FIG. 18.

FIG. 20 is an enlarged, top-sectional view of the release means of FIGS.1 and 3.

FIG. 21 is a side elevational view of another embodiment of the releasemeans of the present invention.

FIG. 22 is an end elevational view of the release means of FIG. 21.

FIG. 23 is a top plan view of the lever arm of FIGS. 21 and 22.

FIG. 24 is a front elevational view of another embodiment of the releasemeans of the invention.

FIG. 25 is a top plan view of an embodiment of the release means of FIG.24.

FIG. 26 is a top plan view of another embodiment of the release means ofFIG. 24.

FIG. 27 is top plan view of another embodiment of the release means ofFIG. 24.

FIG. 28 is a top plan view of another embodiment of the release means ofFIG. 24.

FIG. 29 is a front elevational view of an embodiment of the releasemeans and linearizing means of the present invention mounted on therotating valve assembly of the present invention.

FIG. 30 is an enlarged front elevational view of the release means andlinearizing means of FIG. 29 showing the release means holding the valvein the closed position.

FIG. 31 is a view of FIG. 30 showing the release means in the rupturedor buckled position after a pressure-relieving event has occurred andthe valve has moved to the open position.

FIG. 32 is a view along line 32--32 of FIG. 31.

FIG. 33 is an enlarged sectional view of an embodiment of the latch ofthe present invention.

FIG. 34 is an enlarged view of the buckling pin of FIGS. 29-31 and itsend connections.

FIG. 35 is a replication of FIG. 34 used for additional description andexplanation.

FIG. 36 is an elevational view of another embodiment of the releasemeans of FIG. 30.

FIG. 37 is an elevational view of another embodiment of the releasemeans of FIG. 30.

FIG. 38 is an elevational view of another embodiment of the releasemeans.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will now be described withreference to the drawings. Like reference numerals or characters referto like or corresponding parts throughout the drawings and thedescription.

FIGS. 1-38 present embodiments of the rotatable valve assembly,generally designated 20, of the present invention. Although a preferredembodiment of the rotatable valve assembly 20, described herein tofacilitate an enabling understanding of the invention, is used as apressure relieving device which may be used to replace rupture disks,reverse buckling rupture disks, right angle relief valves, and the like,it is intended to be understood that the invention may be adapted tomany fluid pressure and flow control applications, as would be known toone skilled in the art in view of the disclosure contained herein.

Referring to the example of FIGS. 1 and 2, the assembly 20 may begenerally described as including a housing 22, a valve 24, mountingmeans 26 for rotatably mounting the valve 24 in the housing 22 about arotational axis 28, and power means 30 for rotating the valve 24 betweena closed position 32 and an open position 34. In the more preferredembodiments, the power means 30 comprises conversion means 36 forconverting fluid pressure in the housing 22 into torque exerted on ashaft 38, and the assembly 20 includes release means 40 located outsidethe housing 22, for preventing rotation of the shaft 38 and valve 24from the closed position when the torque exerted on the shaft 38 isbelow a selected magnitude and for releasing the shaft 38 in order toallow rotation of the shaft 38 and valve 24 to the open position 34 whenthe torque exerted on the shaft 38 exceeds a selected magnitude.

The housing 22 has an inlet 46 and an outlet 48 defining a fluidpassageway 50 through the housing 22. The inlet 46 of the housing 22receives fluid and pressure from a fluid pressure source (notillustrated), such as a vessel or piping. In the more preferredembodiments, the shaft 38 has an outside end 52 extending through thehousing 22 and the shaft 38 is rotatable with the valve 24 about therotational axis 28.

The preferred release means 40 includes deformable means 54 for makingdeformable contact between the housing 22 and the shaft 38. Thedeformable means 54 may be a pin, beam, bar, plate, disk, spring, orcomparable rupturable or deformable structure. The deformable means 54may be a permanently or irreversibly deformable structure, such as a pinor beam which bends or ruptures. In the prototype assembly 20, thedeformable means 54 makes deformable contact between the outside 56 ofthe housing 22. and an outside end 52 of the shaft 38. By outside 56 ofthe housing 22 is meant an area of the housing 22, or connectiontherewith, which is not exposed to or in direct operating contact withthe fluid contained inside the housing 22; and which may be accessedwithout opening the housing 22 and exposing the fluid contactingportions of the housing 22 to the outside atmosphere, and without takingthe assembly 20 out of service.

Referring to the example of FIG. 3, in one embodiment the mounting means26 includes a shaft 38 having a second outside end 58 extending throughthe housing 22; and the release means 40 includes a second deformablemeans 60 for making deformable contact between the housing 22 and theshaft 38, as previously discussed. The shaft 38 may be a single,continuous shaft extending across a face of or through the valve 24, ormay be one or more shaft ends, axles, ears, or the like which extendfrom the valve 24 through the housing 22. Limit switches, motiondetection switches, or the like may be provided at either or bothoutside ends 52, 58 of the shaft 38 to indicate whether the valve 24 isopen or closed or has been opened or closed.

Referring to the example of FIG. 2, the deformable means includes a pin54, connected between the shaft 38 and the housing 22, which breaks whenthe torque exerted on the shaft exceeds a selected magnitude. Referringto the example of FIG. 4, in another embodiment, the deformable means 54includes a pin 54, connected between the housing 22 and the shaft 38,which bends when the torque exerted on the shaft 38 exceeds a selectedmagnitude. FIG. 4, also exemplifies a pin or spring 54 which isconnected between the shaft 38 and housing 22 so that the pin 54 isplaced in compression by the torque exerted on the shaft 38. Referringto the example of FIG. 5, the pin or spring 54 is connected between theshaft 38 and housing 22 so that the pin 54 is placed in tension by thetorque exerted on the shaft 38. Referring to the example of FIG. 6, thepin 54 is connected between the shaft 38 and the housing 22 so that thepin 54 is subjected to shear forces by the torque exerted on the shaft38.

FIGS. 2 and 4-7 are simplified, schematic illustrations of exampleembodiments of the release means 40. In the example of FIGS. 2 and 4-6,the release means 40 includes a contact arm 66 having a first end 68connected to the outside end 52 of the shaft 38 and a second end 70spaced away from the rotational axis 28 of the shaft 38; a releasesupport 72 connected to the housing 22; and a pin or spring 54,connected to the release support 72 and obstructing rotation (clockwisein FIGS. 2 and 4-7) of the second end 70 of the contact arm 66. The pinor spring 54 obstructs or prevents rotation of the contact arm 66, shaft38, and valve 24 from the closed position 32 of the valve until thetorque exerted on the shaft 38 exceeds the selected magnitude. Thedimension or distance that the second end 70 of the contact arm 66 isspaced or extended from the rotational axis 28 of the shaft 38 may beselected, in view of the torque exerted on the shaft 38, to adjust theleverage or mechanical advantage created by the distance between therotational axis 28 of the shaft 38 and the second end 70 of contact arm66, and to allow the use of a relatively small pin or spring 54.Depending upon the diameter of the shaft 38 and the torque exerted onand by the shaft, in some applications the second end 70 may be formedin or on the shaft (e.g., a socket for receiving the release means 40)with the contact arm 66 being the distance between the rotational axis28 and the second end 70.

FIGS. 4-7 are simplified, schematic illustrations of additional exampleembodiments of the release means 40 as seen from the left side of FIG.2. Referring to the example of FIG. 4, the pin or spring 54 is disposedon the release support 72 so that the pin is subjected to compressiveforces by the second end 70 of the contact arm 66. This type of pin 54is sometimes referred to as a buckling pin or, if it is a spring, acompression spring. The pin or spring 54 should be secured between therelease support 72 and the second end 70 of the contact arm 66 so thatthe contact arm 66 holds the valve 24 solidly in the closed position 32.The pin 54 should also be secured so that when the pin 54 buckles (orthe spring compresses), it does not interfere with the clockwiserotation of the contact arm 66 and valve 24 from the closed position tothe open position. For example, in the embodiment of FIG. 4, the firstend 62 of the pin or spring 54 may be fastened securely to the releasesupport 72 with the second end 64 of the pin simply contacting thesecond end 70 of the contact arm 66 or being received in a recess 71 inthe second end 70 of the contact arm 66 so that the second end 64 of thepin 54 is easily detached from connection with the contact arm 66 whenthe pin 54 buckles or bends.

Referring to the example of FIG. 5, the pin or spring 54 is connectedbetween the release support 72 and the second end 70 of the contact arm66 so that the pin is placed in tension by the contact arm 66. Thetension pin 54 may be replaced by a tension wire or a tension spring.The preferred tension pin or spring 54 has a first end 62 which issecured, such as by clamps, bolts, screws, or the like to the releasesupport 72 and a second end 64 which is secured, such as by clamps,bolts, screws, or the like to the contact arm 66. Alternatively, aperforation or hole may be made in the contact arm 66 and/or releasesupport 72, the perforation being large enough to pass the tension pin54 with the appropriate end(s) of the tension pin being enlarged orfastened so that it will not pass through the perforation when the pinis placed in tension. Referring to FIG. 5, as the valve and contact arm66 attempt to rotate clockwise from the closed position to the openposition, the pin or spring 54 is placed in tension until the torqueexerted on the valve 24 and pin 54 exceeds the selected rupture pressureof the tension pin 54 or the restraining force of the tension spring. Asin the other embodiments of the release means 40, the tension pin orspring 54 should be adjustably connected between the contact arm 66 andrelease support 72 in such a manner that the valve 24 is held securelyin a closed position until the pin 54 ruptures or otherwise releases thevalve 24.

Referring to the example of FIG. 6, in another embodiment, the pin 54 isdisposed on the release support 72 so as to be subjected to shear forcesby the second end 70 of the contact arm 66. In the example of FIG. 6,the shear pin 54 is securely fastened to the release support 72 andextends upwardly therefrom. The second end 70 of the contact arm 66 hasan extension 73 which extends about perpendicularly from the contact arm66 into contact with the pin 54 adjacent the connecting point of the pin54 to the release support 72. The extension 73 exerts a shearing force(about perpendicular to the length of the pin) on the pin 54 at itsconnection to the release support 72. As in the other embodiments of therelease means 40, the relative positioning of the shear pin 54 andcontact arm extension 73 should be adjustable and adjusted to hold thevalve 24 securely in the closed position until the torque exerted on thevalve exceeds the selected magnitude at which the pin 54 should shearand the valve should open.

Referring to the example of FIG. 7, in another preferred embodiment, therelease means 40 includes a magnetic catch 74. The magnetic catch 74 hasa first magnetic element 76 located on the second end 70 of the contactarm 66 and a second magnetic element 78 located on the release support72. The first and second magnetic elements 76, 78 are oriented so thattheir magnetic attraction holds the contact arm 66 and valve 24 in theclosed position until the torque exerted on the valve 24 and shaft 38exceeds the selected magnitude. The first and second magnetic elements76, 78 may be permanent magnets or electromagnets, although permanentmagnets are preferred. One of the first and second magnetic elements 76,78 may be a non-magnetized material, such as a ferro-magnetic metal,which is attracted to the magnetization of the other elements 76, 78. Asin the other embodiments of the release means 40, the location of thefirst and second magnetic elements 76, 78 should be adjustable so thatthe valve 24 is held securely in the closed position in order to preventleakage of fluid around the valve and to prevent movement and/orchattering of the valve in the housing 22. The magnetic strengths of themagnetic elements 76, 78 should be selected to hold the valve in theclosed position until the torque exerted on the valve 24, shaft 38, andcontact arm 66 exceeds the selected magnitude. The magnetic catch 74provides a repeatable release means 40 which allows the valve 24 to berestored to the closed position without replacement parts and which maybe used many times without losing any accuracy in the amount of torqueor fluid pressure required to move the valve 24 from the closed positionto the open position.

Referring to the example of FIGS. 2 and 3, in the prototype assembly 20,which is a pressure relieving device, the conversion means 36 isprovided by the valve 24 and the mounting means 26 is provided by theshaft 38. The preferred conversion means 36 applies greater force of thefluid pressure to the valve 24 on one side of the rotational axis 28 ofthe shaft 38. The conversion means 36 may be any valve placement, valveshape, valve seat shape or structure, housing shape or structure, fluidpassageway 50 shape or structure, valve actuator, or the like, whichapplies the fluid pressure in the housing inlet 46 to the valve 24 insuch a manner as to create a moment or torque about the rotational axis28 of the valve 24 and/or shaft 38. In the prototype assembly 20, thisis accomplished by using a butterfly or disk valve 24 and mounting thevalve 24 for eccentric rotation in the passageway 50. The rotationalaxis 28 of the shaft 38 and valve 24 is offset from the diameter 84 ofthe valve 24. The first portion 124 of the valve 24 on the first side ofthe rotational axis 28 is larger and has greater area exposed to theinlet fluid pressure than the second portion 128 of the valve 24 on thesecond side of the rotational axis 28. This creates a moment and torqueabout the rotational axis 28 and shaft 38. This arrangement has anotheradvantage in that the shaft 38 partially balances the fluid pressure oneither side of the rotational axis 28 and shaft 38 and therefore reducesthe pressure which the valve 24 must directly resist to seal, therebyreducing the chatter or simmer experienced in some types of pressurerelieving valves, such as right angle relief valves.

Referring to example FIGS. 8-15, a more preferred embodiment of therotatable valve assembly 20 will now be discussed. Referring to theexample of FIGS. 8 and 9, the valve 24 has an inlet face 88, an outletface 90, and a circumference 92 extending around the valve 24 betweenthe inlet and outlet faces 88, 90. The inlet face 88 faces into thehousing inlet 46 in the closed position 32 of the valve 24, the outletface 90 faces into the housing outlet 48 in the closed position 32 ofthe valve 24, and the valve circumference 92 faces the surrounding orcircumjacent fluid passageway 50 and defines a space or gap 94 (FIG. 10)between the valve circumference 92 and the fluid passageway 50 in theclosed position 32 of the valve 24. The preferred gap 94 is annular andof relatively constant dimension (between the housing 22 andcircumference 92). The dimension of the gap or space 94 may be of anymagnitude which will allow the valve 24 to rotate in the housing 22 andfluid passageway 50 and accommodate the seal 96 described below, orother desired seal structures, as would be known to one skilled in theart in view of the disclosure contained herein.

Referring to example FIGS. 10-12, the assembly 20 includes a seal 96 forsealing the gap 94 between the valve circumference 92 and the fluidpassageway 50 in the closed position of the valve 24. The preferred seal96 includes a support edge 98 which is sealingly secured to the fluidpassageway 50, a sealing edge 100 which extends inwardly into the fluidpassageway 50 from the support edge 98 and into contact with the valvecircumference 92 in the closed position 32 of the valve 24. A seal body102 is connected between the support edge 98 and the sealing edge 100and displaces the sealing edge 100 axially towards the inlet face 88 ofthe valve 24 and towards the housing inlet 46 from the support edge 98.The preferred seal 96 extends continuously around the fluid passageway50.

Referring to example FIG. 10, the support edge 98 of the seal 96 definesa support edge plane 104 extending transversely across the fluidpassageway 50 of the housing 22. The sealing edge 100 of the seal 96defines a sealing edge plane 106 extending transversely across the fluidpassageway 50 of the housing 22. The sealing edge plane 106 is spacedaway from the support edge plane 104 towards the housing inlet 46 inorder to increase the resilience of the sealing edge 100 and to enhancethe ability of the sealing edge to seal against the circumference 92 ofthe valve 24, as will be further discussed below.

Referring to example FIG. 13, in the preferred assembly, the fluidpassageway 50 of housing 22 has an inside diameter 108, the seal supportedge 98 has an outside diameter 110, and the sealing edge 100 has aninside diameter 112. The inside diameter 108 of the housing 22circumjacent, or in diametrical alignment, with the seal body 102 andsealing edge 100 is larger than the outside diameter 110 of the supportedge 98 to allow fluid and fluid pressure entering the housing inlet 46to have access to the outside diameter 114 of the seal body 102. Thepreferred housing inside diameter 108 should be sufficiently larger thanthe support edge outside diameter 110 that the ability of the seal body102 and sealing edge 100 to flex or move radially is not impaired. Whenthe valve is in the closed position 32, the fluid pressure in thehousing inlet 46 will exert a radially inward force on the outsidediameter 114 of the seal body 102 forcing the sealing edge 100 intovirtually bubble-tight contact with the valve circumference 92.Normally, when the valve 24 is in the closed position 32, the pressurein the housing outlet 48 will be substantially lower than the pressurein the housing inlet 46 and the extension of the seal body 102 andsealing edge 100 away from the support edge 98 will allow thedifferential pressure between the inlet 46 and outlet 48 to act acrossthe seal body 102 and force the sealing edge 100 into sealing engagementwith the valve circumference 92.

Referring to the example of FIGS. 11-13, the preferred seal body 102 hasan outside diameter 114 which is concave or otherwise recessed in radialcross section in order to increase the radial resilience of the seal andto enhance the ability of the seal 96 to use the inlet pressure and/ordifferential pressure across the valve 24 to force the sealing edge 100into virtually bubble-tight engagement with the valve circumference 92.

Referring to the example of FIG. 12, the sealing edge 100 of the seal 96has a convex protuberance 118 in radial cross section in order to make apoint or line contact around the valve circumference 92 in the closedposition of the valve and thereby reduce the surface area and thefrictional forces exerted on the valve 24 and circumference 92 by theseal 96. The sealing edge 100 may have any protuberant shape in radialcross section which will minimize the axial dimension and the surfacearea of the contact between the sealing edge 100 and the valvecircumference 92 while achieving an acceptable sealing function. Morepreferably, as exemplified in FIG. 11, the sealing edge 100 has a vertex116 in radial cross section and the vertex 116 makes a point contact orline contact of minimal axial dimension around the valve circumference92 in order to reduce the surface area and the frictional forces exertedon the valve 24 by the seal 96 and to thereby reduce the torque requiredto open and close the valve 24.

Referring to the example of FIGS. 13-15, the rotational axis 28 of thevalve 24 defines a first portion 122 of the seal 96 and sealing edge 100and a first portion 124 of the valve 24 and valve circumference 92 onone side of the rotational axis 28 and a second portion 126 of the seal96 and sealing edge 100 and a second portion 128 of the valve 24 andvalve circumference 92 on the other side of the rotational axis 28. Aspreviously discussed, the first portion 124 of the valve 24 rotates intothe outlet 48 of the housing 22 when the valve rotates from the closedposition 32 to the open position 34. The axial dimension 130 of thevalve circumference 92 in contact with the sealing edge 100 in theclosed position 32 of the valve 24 defines a sealing surface, alsodesignated 130, which is selected or sized so that the first portion 122of the sealing edge 100 breaks contact with the first portion 124 of thevalve circumference 92 and sealing surface 130 simultaneously with thesecond portion 126 of the sealing edge 100 breaking contact with thesecond portion 128 of the valve circumference 92 and sealing surface 130(as illustrated in FIG. 14) as the valve 24 rotates from the closedposition 32 to the open position 34. More specifically, the insidediameter 112 of the sealing edge 100 is selected or sized in conjunctionwith the selection of the axial dimension 130 of the valve circumferencesealing surface 130 and the selection or sizing of the placement of therotational axis 28 on the valve 24 so that the first and second portions122, 126 of the sealing edge break contact with the first and secondportions 124, 128 of the valve circumference sealing surface 130simultaneously as the valve rotates from the closed position 32 to theopen position 34. This simultaneous opening of both portions 124, 128 ofthe valve prevents the valve from hanging in a partially open position.If any portion of the valve circumference 92 breaks contact with thesealing edge 112 prior to the remainder of the valve circumference 92,the pressure in the housing inlet 46 may leak down before the releasemeans 40 has an opportunity to fully release the valve 24 for rotationto the open position 34. For example, if the release means is a bucklingpin 54, the premature opening of either portion 124, 128 of the valve 24may cause the pin 54 to partially buckle. This can result in the valvebeing left in a partially open position with no external indication,thereby creating a potentially dangerous or hazardous situation.

In the prototype assembly 20, the sealing surface 130 has a constant andequal axial dimension on both portions 124, 128 of the valve and thesealing surface 130 is of constant outside diameter, i.e., the outsidediameter of the sealing surface 130 is about parallel with thelongitudinal axis 136 of the housing 22 and valve 24. The dimensions andshaping of the sealing surface 130 may be altered in conjunction withthe placement of the rotational axis 28 on the valve 24 and the sizingand shaping of the inside diameter 112 of the sealing edge 100 toachieve other designs which facilitate the simultaneous opening of bothportions 124, 128 of the valve 24, as would be known to one skilled inthe art in view of the disclosure contained herein.

Referring to the example of FIGS. 14 and 15, in the preferred assembly,the second portion 128 of the valve circumference 92 has a bevel 132, orbeveled portion 132, so that the valve circumference 92 at the outletface 90 of the valve 24 is smaller than the remainder of the valvecircumference 92, i.e., smaller than the sealing surface 130 of thevalve circumference 92, and the outlet face 90 of the second portion 128of the valve 24 does not contact the second portion 126 of the seal 96as the valve 24 rotates from the open position 34 to the closed position32. In other words, the beveled portion 132 has a large enough anglewith respect to the longitudinal axis 136 of the housing that the insidediameter 112 of the sealing edge 100 is greater in dimension than theoutside diameter of the outlet face 90 of the valve 24. Therefore, theoutlet face 90 of the valve does not contact the second portion 126 ofthe seal and push it into the housing outlet 48 or otherwise deform theseal 96 as the valve 24 is returned from the open position 34 to theclosed position 32. The beveled portion 132 should extend around thesecond portion 128 of the valve circumference 92 and beyond theantipodes of the rotational axis 28 of the valve 24. In the prototypevalve 24, the beveled portion 132 extends entirely around the valvecircumference 92.

Referring to example FIGS. 9 and 10, the prototype housing has an inlet46 of greater diameter than the outlet 48. The juncture of the housinginlet 46 and housing outlet 48 creates an annular ledge or seatingsurface 140 in the fluid passageway 50. The valve 24 is positioned sothat it is in general diametrical alignment with the housing seatingsurface 140 in the closed position 32 of the valve 24. The prototypeseal 96 includes an annular retainer 142 which extends outwardly fromthe seal support edge 98 for sealingly retaining the seal 96 in thefluid passageway 50. In the prototype assembly 20, the annular retainer142 is made of a relatively rigid or stiff material and is press-fit orfriction-fit against the housing seating surface 140. The prototyperetainer 142 is generally L-shaped in radial cross section and is sizedto allow unrestricted access of the inlet pressure to the outsidediameter 114 of the seal body 102. In the seal exemplified in FIGS.9-15, the support edge 98 of the seal 96 is adhesively bonded to theradial edge 144 (FIG. 10) of the retainer 142. Depending upon theservice conditions, the retainer 142 may be made of carbon steel,stainless steel, or like materials. The preferred seal 96, seal body102, and sealing edge 100 are made of a resilient polymer, plastic, orelastomer, such as Viton®. Rather than bonding the seal body 102 to theretainer 142, the retainer 142 may be completely encapsulated or coatedby the seal 96, as would be known to one skilled in the art in view ofthe disclosure contained herein.

The use of the seal 96 discussed above creates a rotatable valveassembly 20 in which neither the housing 22 nor the valve 24continuously wipes or drags against a large surface area of a seal asthe valve is rotated. This greatly reduces the frictional forces whichmust be overcome to rotate the valve 24 and also creates a rotatablevalve assembly 20 in which the torque required to initiate rotation ofthe valve assembly does not increase as the valve is left in a closedposition for extended periods of time. The previously described seal 96may be incorporated into virtually any type of rotatable valve assemblyin which it is desired to reduce the frictional forces required to open,close, or rotate the valve; and may be used without the conversion means36 and with the various known types of power means 30, such as manual,hydraulic, pneumatic, and electric valve actuators.

Referring to the example of FIGS. 16-19, the assembly 20 may alsoinclude reclosure means 152, located outside the housing 22, forreturning the valve 24 to the closed position 32 after the valve 24 hasbeen opened. The reclosure means 152 is particularly useful where theassembly 20 is used as a pressure relieving device, in that, after theexcessive pressure has been relieved, the reclosure means 152 willautomatically return the valve 24 to the closed position 32. It iscontemplated that the assembly 20 and reclosure means 152 will beparticularly useful with the release means 40 having a magnetic catch 74(FIGS. 7, 25, and 37), in that the reclosure means 152 mayautomatically, without the aid of a human operator, reset the magneticcatch 74 and valve 24 to the closed position until another overpressurecondition exerts torque about the rotational axis 28 and shaft 38 whichexceeds the selected magnitude required to open the magnetic catch 74.

The reclosure means 152 may be any form of spring-loaded actuator,pneumatically-operated actuator, electrically-operated actuator,hydraulically-operated actuator, or weight-biased actuator. The strengthof the reclosure means 152 should be selected, in view of the torque orfluid pressure at which the release means 40 is designed to allow thevalve 24 to open, to reclose the valve 24 without interfering with thepressure relieving design or capability of the valve 24, as would beknown to one skilled in the art in view of the disclosure containedherein. The reclosure means 152 may be located at the same shaft end 52,58 as the release means 40 or at the opposite outside shaft end.

Referring to the example of FIG. 16, in one embodiment, the reclosuremeans 152 comprises a torsion spring 154 connected between the outsideend 52 of the shaft 38 and a torsion spring housing 156 connected to theoutside of the housing 22 adjacent the shaft 38.

Referring to the example of FIG. 17, in another embodiment, thereclosure means 152 includes a first magnetic element 158 having north(N) and south (S) magnetic poles disposed in the outside end 52 of theshaft 38. A second magnetic element 160 having north (N) and south (S)magnetic poles is disposed in the housing 22 or in a magnet housing 162extending from the outside of the housing 22 adjacent the shaft 38. Thefirst and second magnetic elements may be electromagnets or the like,but are permanent magnets in the preferred embodiment. The first andsecond magnetic elements 158, 160 are oriented so that like magneticpoles of the first and second magnetic elements 158, 160 bias the shaft38 and valve 24 from the open position 34 to the closed position 32after the overpressure and torque forcing the valve 24 from the closedposition to the open position has subsided.

Referring to the example of FIGS. 18 and 19, in another embodiment, thereclosure means 152 includes a reclosure arm 164 connected to andextending from the outside end 52 of the shaft 38. A counterweight 166is connected to the reclosure arm 164 for urging the shaft 38 and valve24 from the open position 34 to the closed position 32. Preferably, thereclosure arm 164 is connected to the outside end 52 of the shaft 38with a counterweight housing 168. The preferred counterweight housing168 is rotationally positionable on the shaft end 52. For example, asillustrated in FIG. 19, the counterweight housing 168 may be acylindrically shaped extension which fits over the outside end 52 of theshaft 38 and has a set screw 170, or other fastening device, forselectably securing the position of the counterweight housing 168 on theshaft end 52. The set screw 170 may be loosened and the housing 168rotated with respect to the shaft end 52 in order to adjust theorientation of the reclosure arm 164 and counterweight 166 with respectto the housing 22 and valve 24. The preferred reclosure arm 164 isadjustably connected to the counterweight housing 168 so that thedistance from the rotational axis 28 of the shaft 38 to thecounterweight 166 may be adjusted in order to adjust the magnitude ofthe force or torque the counterweight 166 exerts in biasing the valve 24towards the closed position 32. In the example FIG. 19, the reclosurearm 164 extends through a slot or other transverse (to the rotationalaxis 28) passageway 172 through the housing 168 and a second set screw174 is adjustably extendable through the housing 168 into contact withthe reclosure arm 164 to secure the arm 164 in a selected position.Preferably, the counterweight 166 is detachable from the reclosure arm164 so that various sizes or weights of counterweights 166 may be usedto adjust the force or torque with which the reclosure arm 164 biasesthe valve 24 from the open position 34 towards the closed position 32.

Referring to the example of FIG. 20, in another embodiment, the releasemeans 40 includes a pin or beam 54 connected between the shaft 38 andthe housing 22 and having an unsupported area 180 extending between theshaft 38 and the housing 22. The unsupported area 180 reduces the torqueor force magnitude required to deform or rupture the pin 54 to amagnitude below the torque or force magnitude required to shear the pin54. It is contemplated that the predictability of the force required torupture the pin 54 becomes more accurate or reliable as the length ofthe unsupported area 180 increases.

The pin 54 extends about diametrically through a hole 184 in the outsideend 52 of the shaft 38. A support housing 186 is connected to thehousing 22 around the outside end 52 of the shaft 38. The supporthousing 186 includes a slot or hole 188 which may be aligned with atleast one end of the pin 54 so that an end of the pin 54 may be extendedthrough both the shaft 38 and support housing 186 in order to lock orsecure the valve 24 in the closed position 32. The pin 54 and theunsupported area 180 between the outside end of the shaft 38 and theadjacent support housing 186 should be selected or sized so that the pin54 will rupture when a preselected magnitude of torque is applied to thevalve 24 and shaft 38. The support housing 186 and pin 54 may bedesigned so that the pin 54 passes through the shaft and through thesupport housing 186 on both sides of the shaft 38, as illustrated inFIG. 20, if it is desired to increase the torque required to rupture thepin 54. Also, a second support housing 190 may be provided at the secondoutside end 58 of the shaft 38 and provision made for providing pins 54,192 at both ends 52, 58 of the shaft 38 if it is desired to furtherincrease the torque required the shaft 38 and valve 24 from the closedposition 32 (FIG. 3). The relative positioning of the support housing(s)186, 190 and slot(s) 184, 188 should be adjustable to ensure snugengagement of the pin 54 in the slot(s) and to thereby securely hold thevalve 24 in the closed position 32 at torques below the desired rupturetorque, as would be known to one skilled in the art in view ofdisclosure contained herein.

Referring to the example of FIGS. 21 and 22, in another prototypeembodiment of the release means 40, the release support 72 includes aframe 194 connected to the outside 56 of the housing 22. A deformable orrupturable pin 54 is mounted on the release support 72 at a point spacedaway from the rotational axis 28 of the shaft 38. A contact arm 66 has afirst end 68 connected to the outside end 52 of the shaft 38 and asecond end 70 which extends away from the shaft end 58 and contacts thepin 54 at a deformation initiation point 182. In the prototype assembly20, the pin 54 is simply supported, i.e., the first and second ends 196,198 of the pin 54 are supported with the deformation initiation point182 and the remainder of the pin 54 being unsupported. The pin 54 andthe distance between the supported ends 196, 198 of the pins should beselected or sized to rupture or deform when the selected torque existson the shaft 38 and arm 66. The placement of the release support 72 anddistance of the deformation initiation point 182 from the rotationalaxis 28, and the length of arm 60 may also be sized or selected inconjunction with the strength of the pin 54 to allow the valve 24 andshaft 38 to rotate when the fluid pressure exerts a predeterminedmagnitude of torque on the valve 24 and shaft 38. A second releasesupport, second contact arm, etc. may be provided at the second outsideend 58 of the shaft 28 (not illustrated) if desired or necessary for aspecific application, as would be known to one skilled in the art inview of the disclosure contained herein.

In another prototype embodiment of the release means 40, referring tothe example of FIGS. 21-23, the second end 70 of the contact arm 66contacts a lever arm 200 which extends between the contact arm 66 andpin 54 in order to further increase the mechanical advantage at thelocation of the pin 54 and reduce the strength of the pin 54 necessaryto hold the valve 24 in the closed position 32. This is particularlyuseful when the assembly 20 is to be used in high pressure applications.Although the lever arm 200 may take various shapes and configurations toadapt to a specific situation, as will be known to one skilled in theart in view of the disclosure contained herein, and as further discussedbelow, in the prototype assembly 20 of FIGS. 21-23, the lever arm 200 isgenerally L-shaped. The lever arm 200 has a short leg 202 which contactsthe arm 66 and a long leg 204 which extends perpendicularly from theshort leg 202 into contact with the pin 54. The release support 72includes a position adjustment mechanism 206, such as a set screw,threaded bolt, or the like, for adjusting the position of pin 54 and theengagement between the pin 54 and lever arm 200. The pin's positionshould be adjusted so that the valve 24 is held sealingly engaged withthe housing 22 until the torque about shaft 38 exceeds the desiredrupture torque at which the valve 24 is to open.

A hinge pin 208 extends through juncture of the short and long legs 202,204 and creates an axis of rotation of the lever arm 200 which is aboutperpendicular to the plane of the lever arm 200. The hinge pin 208 hasreceptacle 210 (FIG. 21) which connects the hinge pin 208 to the outsideof the housing 22. In the prototype lever arm 200, the free end 212 ofthe long leg 204 has a pointed, knife-like edge which contacts the pin54 at the deformation initiation point 182 (FIG. 23). As previouslymentioned, the pin 54 may be selected to rupture or to deform (i.e.,bend) when subjected to a preselected force, thereby freeing the arm 66and allowing the arm 66, shaft 38, and valve 24 to rotate to the openposition 34 of the valve 24. In the prototype assembly 20, a handle 214is provided for lifting or carrying the assembly 20, as the assembly 20may be large and heavy. As indicated in FIG. 22, replacement pins 216may be stored in the handle 214.

FIGS. 24-28 exemplify another preferred embodiment of the release means40, which does not require a housing 22 as large as the previouslydiscussed embodiments, particularly along the flow axis 136. In theembodiments of FIGS. 24-28, the contact arm 66 has a first end 68connected to the outside end 52 of the shaft 38 and a second end 70extending therefrom. The release means 40 includes stanchion 222extending from the outside 56 of the housing 22. Lever arm 224 ispivotably connected to the stanchion 222 so that the lever arm 224 willpivot in a plane about parallel with the pivotal plane of the contactarm 66, the pivotal plane of the lever arm 224 being closer to thehousing 22 so that the lever arm 224 is free to pivot between thecontact arm 66 and the housing 22. The lever arm 224 has a first end 226extending away from the stanchion and shaft 38 and a second end 228extending from the stanchion 222 toward the shaft 38, the distance fromthe stanchion 222 to the second end 228 being greater than the distanceto the first end 226. A post 230 extends from one of the second end 70of the contact arm 66 or the first end 226 of the lever arm 224 intocontact with the other (in the prototype assembly 20 the post is fixedlyattached to the second end 70 of the contact arm 66). A release support72 is connected to the housing 22 through the contact arm 66 and shaft38, i.e., the release support 72 is connected to the contact arm 66 nearthe first end 68 of the contact arm 66 and between the shaft 38 and thestanchion 222, such that the release support 72 is in the rotationalpath of the second end 228 of the lever arm 224. As the shaft rotates,the post 230 moves the first end 226 of the lever arm 224, and therotatable connection of the lever arm 224 to the stanchion 222 acts as afulcrum in transmitting the motion of the post 230 and first end 226 tothe second end 228 of the lever arm 224. The second end 228 of the leverarm 224 is in contact with a pin, spring, or magnet disposed on therelease support 72 and which is selected in conjunction with the sizingof the contact arm 66 and lever arm 224 to restrain rotation of theshaft 38 until the torque about the rotational axis 28 and shaft 38exceeds a selected magnitude. As in the embodiments of the release means40 of FIGS. 2-7 and 20-22, in the embodiments of FIGS. 24-28, thevarious forms of the pin, spring, and magnet should be secured to thecontact arm 66 and/or release support 72 so that the release means 40does not interfere with the rotation of the contact arm 66, lever arm224, and valve 24 from the closed position to the open position when thetorque exerted on the shaft 38 and release means 40 exceeds the selectedmagnitude; and the relative positioning of the pin, spring, magnet,contact arm 66, and lever arm 224 should be adjustable and adjusted tohold the valve 24 securely in the closed position until the torqueexerted on the shaft 38 exceeds the selected magnitude.

Referring to the example embodiment of FIG. 25, a first magnetic element76 is connected to the release support 72 and a second magnetic element78 is connected to the second 228 of the lever arm 224, the attractionof the magnetic elements preventing the second end 228 of the lever arm224 from rotating (counterclockwise in FIG. 25) away from the releasesupport 72 until the torque about shaft 38 (counterclockwise in FIG. 25)exceeds a preselected magnitude.

Referring to the example embodiment of FIG. 26, the release support 72supports a pin 54 which prevents the second end 228 of the lever arm 224from rotating (counterclockwise in FIG. 26) and allowing the shaft 38 torotate (counterclockwise in FIG. 26) until the torque about the shaft 38exceeds a preselected magnitude and breaks the pin 54. The pin 54 may besimply supported or cantilevered on the release support 72. If the pin54 is cantilevered, the release support 72 may be eliminated bycantilevering the pin 54 from the contact arm 66 into obstruction withthe second end 228 of the lever arm 224, as indicated by the solid linedrawing of the pin 54 in FIG. 26.

Referring to the example embodiment of FIG. 27, a tension pin or wire234 has a first end 236 connected to the release support 72 and a secondend 238 connected to the second end 228 of the lever arm 224 such thatrotation of the shaft 38 (counterclockwise in FIG. 27) is restrained bythe tensile strength of the tension pin 234 until the torque about theshaft 38 exceeds the tensile strength of the wire 234 and breaks thewire 234. The tension pin 234 may be replaced with a tension spring 234,as would be known to one skilled in the art in view of the disclosurecontained herein. The tension spring 234 would have the advantage ofautomatically and repeatably restoring the valve 24 to the closedposition without replacement parts.

Referring to the example of FIG. 28, a buckling pin 235 has a first end237 connected to the release support 72 and a second end 239 connectedto the second end 228 of the lever arm 224 such that any rotation of theshaft 38 and valve 24 toward the open position 34 (counterclockwise inFIG. 28) places the buckling pin 235 in compression. The compressivestrength of the buckling pin 235 is selected to resist the rotation ofthe shaft 28 until the torque exceeds the selected magnitude and bucklesor bends the pin 235. The buckling pin 235 may be replaced with acompression spring, as would be known to one skilled in the art in viewof the disclosure contained herein. The compression spring 235 wouldhave the advantage of repeatably restoring the valve 24 to the closedposition without replacement parts.

FIGS. 29-38 exemplify an embodiment of the assembly 20 which includeslinearizing means 240 for converting the forces exerted on the releasemeans 40 or deformable means 54 by the shaft 38 into a substantiallylinear force. The linearizing means may be used with any of the varioustypes of release means 40 previously described and may be used with orwithout the improved valve 24, seal 96, and reclosure means 152 of thepresent invention.

Referring to the example of FIGS. 29-32, the prototype linearizing means240 is supported by release support 72. The release support 72 may bedirectly connected to the housing 22, although in the prototypelinearizing means 240, the release support 72 is mounted in a controlbox 242, which is connected to the housing 22, as would be known to oneskilled in the art in view of the disclosure contained herein. Contactarm 66 has a first end 68 connected to the outside end 52 of shaft 38and a second end 70 extending or spaced away from the rotational axis 28of the shaft 38, as previously discussed. The preferred linearizingmeans 240 includes a piston 244 which is slidably mounted on the releasesupport 72 between the release means 40 and the second end 70 of thecontact arm 66. The piston has a first end 246 for contacting therelease means 40 and a second end 248 for contacting the second end 70of the contact arm 66. The linearizing means 240 includes a passageway250, formed or located on the release support 72, for slidably retainingthe piston 244.

The linearizing means 240 and release support 72 should be designed sothat their alignment and positioning relative to the contact arm may beadjusted, as would be known to one skilled in the art in view of thedisclosure contain herein. In the prototype assembly 20, the releasesupport 72 is adjustably mounted on back plate 252, which is mounted incontrol box 242. Back plate 252 has alignment slots 254 and alignmentbolts, set screws, or other adjustable fasteners 256 which may be usedin conjunction with the slots 254 to align the passageway 250 so thatthe longitudinal axis 258 of the passageway 250 lies on a tangent of therotational arc of the second end 70 of the contact arm 66; and tothereby align the longitudinal axis 260 of the piston 244 with a tangentof the rotational arc of the second end 70 of the contact arm 66.Alignment slot 257 is provided in the back plate 252 for adjustablyreceiving the outside end 52 of the shaft 38. An appropriate fasteningdevice 259, such as a locking nut (best seen in FIG. 32) is provided forsecuring the position of the shaft end 52 in slot 257, as well asassisting in securing the back plate 252 in the control box 242.

Alignment slot 266 is also provided in the contact arm 66. Alignmentslot 266 receives a lock nut 267 or equivalent adjustable fastener andcontact member 268 (best seen in FIG. 32) which contacts the second end248 of the piston 244. The point of contact between contact member 268and piston second end 248 defines the tangent of the rotational arc ofthe contact arm 66 along which the axes 258, 260 of the piston 244 andpassageway 250 are aligned. Therefore, the lock nut 267 and contactmember 268 may be adjustably positioned in alignment slot 266 to adjustthe placement of the rotational arc and tangent and to vary the leverageor mechanical advantage which the contact arm 66 provides. Propertangential alignment of the longitudinal axis 260 of the piston 244converts the rotational motion of the second end 70 of the contact arm66 to a virtually pure linear motion of the piston 244.

Referring to the example of FIGS. 29-32, the piston 244 is slidablebetween an extended position 262 (FIGS. 29 and 30) when the valve 24 isin the closed position 32 and a retracted position 264 (FIGS. 31 and 32)when the valve 24 is in the open position 34. When in the extendedposition 262, the piston 244 holds the valve 24 in the closed position32. When the torque exerted on the shaft 38 exceeds the selectedmagnitude, the release means 40 releases the piston 244 and allows it tomove from the extended position 262 to the retracted position 264. Inorder to prevent the piston 244 from rebounding from the retractedposition 264 to the extended position 262 after a pressure-relievingevent, the release support 72 includes a latch 270 having a first end272 connected to the release support 72 and a second end 274 disposedbetween the second end 248 of the piston and the release means 40 whenthe valve 24 is in the closed position 32 and the piston 244 is in theextended position 262. The latch 270 includes bias means 276 for biasingthe second end 274 of the latch 270 into a position obstructing movementof the piston 244 towards the extended position 262 when the piston 244is in the retracted position 264. The bias means 276 may be provided byvirtually any known mechanical biasing apparatus, such as by pivotablyconnecting the first end 272 to the release support and weighting thesecond end 274 to bias the second end 274 into the obstructing orlatching position. In the prototype assembly 20, the bias means 276includes a spring which biases the second end 274 of the latch 270 intothe latching position. The second end 248 of the piston 244 includes acamming surface 278 which is larger at the free end of the second end248 of the piston 244 and reduces or converges towards the first end 246of the piston 244 such that the camming surface 278 depresses or movesthe latch second end 274 as the piston moves from the extended position262 to the retracted position 264, allowing the piston to move into theretracted position 264. Once the piston 244 and camming surface 278 arein the retracted position, as illustrated in FIG. 31, the latch secondend 274 prevents the piston 244 from returning to the extended positionuntil the latch second end 274 is manually depressed and the piston 244is moved to the extended position 262.

As illustrated in FIGS. 32 and 33, the preferred bias means 276 is acommercially available spring-loaded plunger unit, the plunger servingas the latch second end 274. The preferred bias means 276 is adjustablymounted in latch slot 280 with a jam nut 282 so that the position of theplunger 274 may be adjusted along the piston axis 260. The spring-loadedplunger is threaded into a retainer 284 which threads into the jam nut282 so that the extension of the plunger 274 perpendicularly toward andaway from the piston axis 260 may be adjusted and fixed where desired.The sides of the retainer 284 which face the sides of slot 280 areshaped to allow the retainer to move along the axis of the slot (andpiston axis 260) while preventing the retainer from rotating in the slot280 with the jam nut 282. In the prototype, the sides of the retainer284 within the slot 280 are flattened and generally parallel to the axisof the slot 280 and piston axis 260.

Referring to the example of FIG. 32, the preferred linearizing means 240includes a roller bearing 288, connected to either the second end 70 ofthe contact arm 66 or the second end 248 of the piston 244 for rollinglytransferring the force of the second end 70 of the contact arm 66through the piston 244 to the release means 40. More preferably, theroller bearing 288 is adjustably connected to the second end 70 of thecontact arm 66 with locknut 267, as exemplified in FIG. 32 and replacesthe previously discussed contact member 268. The roller bearing 288prevents the second end 70 of the contact arm 66 from transferringnon-tangential forces to the piston 244, or to the release means 40 ifthe roller bearing 288 is in direct contact with the release means 40(such as if the second end 64 of pin 54 were extended through passageway250 into contact with the roller bearing 288).

FIGS. 29-31, 34 and 35 exemplify the linearizing means 240 used with acompression pin or buckling pin 54. The preferred pin 54 is a bucklingpin which is selected or sized to buckle substantially instantaneouslywhen its buckle pressure is attained. FIGS. 34 and 35 are enlarged viewsof the buckling pin 54 and its connections to the release support 72 andcontact arm 66. The pin 54 has a first end 62 connected to the releasesupport 72, a second end 64 for contacting the contact arm second end70, and a longitudinal axis 294 extending through the first and secondends 62,64. As the contact arm 66 rotates from the closed position 32 tothe open position 34 of the valve 24 (counterclockwise in FIGS. 29-32)the contact arm second end 70 exerts a compressive force on the pin 54.The longitudinal axis 294 of the pin 54 is connected between the releasesupport 72 and the contact arm 66 so that the longitudinal axis 294 ofthe pin 54 lies on a tangent to the rotational arc of the contact armsecond end 70.

More preferably, referring to the example of FIGS. 29-31, 34, and 35,the linearizing means 40 comprises a pin seat 296 connected to therelease support 72 for receiving the first end 62 of the pin 54 and apassageway 250 formed on the release support 72, for slidably supportingthe second end 64 of the pin 54 in contact with the second end 70 of thecontact arm 66. The pin seat 296 and passageway 250 are located to holdthe pin 54 with the longitudinal axis 294 of the pin in alignment with atangent to the rotational arc of the second end 70 of the contact arm 66so that the pin is subjected to a virtually pure linear and compressiveforce as the shaft 38 and second end 70 of the contact arm 66 rotatefrom the closed position 32 to the open position 34 with the valve 24.As previously mentioned, a roller bearing 288 may be connected to thesecond end 70 of the contact arm 66 for rollingly and compressinglycontacting the second end 64 of the pin 54.

More preferably, as previously discussed, the linearizing means 240includes piston 244, slidably mounted in the passageway 250 on therelease support 72 between the pin 54 and the contact arm 66 in such amanner that the piston 244 is slidable coaxially with the longitudinalaxis 294 of the pin 54. As exemplified in FIG. 31, when the piston 244moves from the extended position 262 to the retracted position 264 thepin 54 is compressed or buckled and the piston 244 is latched in theretracted position 264 by latch 270.

Referring to the example of FIGS. 34 and 35, in order to increase thepredictability of the buckling pressure of the compression pin 54, thefirst and second ends 62, 64 of the pin 54 are flat and perpendicular tothe longitudinal axis 294 of the pin 54. The pin seat 296 has a pin seatsocket 300. The pin seat socket 300 has a longitudinal axis whichcoincides with the longitudinal axis 294 of the pin 54 when the pin 54is in the pin seat socket 300. The pin seat socket 300 has a bottomsurface 304 which is flat and perpendicular to the longitudinal axis ofthe pin seat socket 300 so that the flat first end 62 of the pin 54makes full facial contact with the bottom surface 304, as exemplified inFIG. 34. The first end 246 of piston 244 includes a pin socket 306 forreceiving the second end 64 of the pin 54. The pin socket 306 has alongitudinal axis which coincides with the longitudinal axis 294 of thepin 54 when the pin 54 is in the pin socket 306. The pin socket has abottom surface 310 which is flat and perpendicular to the longitudinalaxis of the pin socket 306 so that the flat second end 64 of the pin 54makes full facial contact with the bottom surface 310 as exemplified inFIG. 34.

To further increase the predictability of the buckling pressure of thecompression pin 54, the inside diameter 312 of the pin seat socket 300should be substantially equal to the outside diameter 314 of the firstend 62 of the pin 54 so that the first end 62 of the pin 54 fits tightlyor snugly into the pin seat socket 300; and the inside diameter 316 ofthe pin socket 306 should be substantially equal to the outside diameter318 of the second end 64 of the pin 54 so that the second end 64 of thepin 54 fits tightly or snugly into the pin socket 306, as exemplified inFIG. 35. By a tight or snug fit is meant that the pin ends 62, 64 shouldhave a friction fit with their respective sockets 300, 306 whichrequires the application of force along the longitudinal axis 294 of thepin to insert the pin ends 62, 64 into the sockets 300, 306.

To further increase the predictability of the buckling pressure of thecompression pin 54, the depth 320 of the pin seat socket 300 should beat least three times greater than the outside diameter 314 of the firstend 62 of the pin 54 and the depth 322 of the pin socket 306 should beat least three times greater than the outside diameter of 318 of thesecond end 64 of the pin 54. The inventors have found that bycontrolling the pin end 62, 64 and socket 300, 306 sizing and structuralconfigurations as described above, the buckling pressure of the pin canbe repeatably predicted within plus or minus one psi. For example, inexperimental testing buckling pins which were rated to buckle at 34 psiwere all found to buckle within a range of 33-35 psi.

Referring to the example embodiment of FIG. 36, the linearizing means240 is adapted for use with a shear pin 54. A pin support 324 isconnected to the release support 72 for receiving the first end 62 ofthe pin 54 and securely holding the pin 54 with the longitudinal axis294 of the pin 54 perpendicular to a tangent of the rotational arc ofthe second end 70 of the contact arm 66. The piston 244 is slidablymounted in the passageway 250 along a tangent of the rotational arc ofthe second end 70 of the contact arm 66. The first end 246 of the piston244 contacts the shear pin 54 and the second end 248 of the piston 244contacts the second end 70 of the contact arm 66. The shear pin 54 holdsthe piston 244 in the extended position 262 until the torque exerted onthe shaft 38 exceeds the preselected magnitude at which the pin 54shears and allows the piston to travel (to the left in FIG. 36) to theretracted position 264 and the contact arm 66 and valve 24 to rotate(counterclockwise in FIG. 36) to the open position 34. The previouslydiscussed latch 270 may be provided to latch the piston in the retractedposition 264. It is contemplated that the linearizing means 240, whenused with a shear pin 54 as previously described, will provide for morepredictable and repeatable shear pressure because the linearizing means240 will exert the shearing force in a direction more preciselyperpendicular to the longitudinal axis 294 of the shear pin 54. Thepositioning of the pin support 324 on the release support 72 and/or thepositioning of the pin 54 in the pin support 324 should be adjustable toallow for proper alignment, of the pin 54 with the linearizing means 240and/or piston 244.

As in the embodiments of the release means 40 of FIGS. 2-7, 20-22, and24-28, in the embodiments of FIGS. 29-38, the various forms of therelease means 40, be it a pin, spring, or magnet, as well as thelinearizing means 240, should be secured to the contact arm 66 and/orrelease support 72 in such a manner that they do not interfere with therotation of the contact arm 66 and valve 24 from the closed position 32to the open position 34; and the relative positioning of the releasemeans 40, contact arm 66, and linearizing means 240 should be adjustableand adjusted to hold the valve securely in the closed position 32 untilthe torque exerted on the shaft 38 exceeds the selected magnitude. Therelease means 40 and linearizing means 240 should be selected andadjusted so there is virtually no rotation of the valve 24 until thetorque exerted on the shaft 38 exceeds the selected magnitude at whichthe valve 24 should as nearly as possible "snap" to the fully openedposition 34.

Referring to the example embodiment of FIGS. 29-31, the pin seat 296 hasexternal threads which allow the pin seat to be adjusted along thelongitudinal axis 294 of the pin 54 until the pin 54 securely restrainsthe contact arm 66 and valve 24 in the closed position. The pin seat 296threadedly engages the internal threads of a collar 326. The collar 326is securely fastened to the back plate 252 so that the pin seat 296 andpassageway 250 may be simultaneously aligned with the tangent of therotational arc of the second end 70 of the contact arm 66, as previouslydiscussed. The free end 328 of the pin seat 296 which extends out of thecollar 326 on the opposite side of the pin 54 is secured against motionby a stop ring 330. More preferably, an antivibration spring 332 isplaced around the free end 328 of the pin seat 296 between the stop ring330 and collar 326 to prevent the stop ring 330 and pin seat 296 fromchanging position when the assembly 20 is subjected to vibration, aswould be known to one skilled in the art in view of the disclosurecontained herein.

Referring to the example embodiment of FIG. 37, the linearizing means240 may be used with a magnetic catch 74 having a first magnetic element76 and a second magnetic element 78 located on the release support 72.In the example embodiment, a passageway 333 extends through the secondmagnetic element 78 and the second magnetic element 78 is fixedlysecured to the release support 72. The passageway 333 should be alignedwith the passageway 250 so that the passageway 333 effectively extendsthe passageway 250 through the second magnetic element 78, and thepiston 244 may move through both passageways 250, 333 as it is movedbetween the extended and retracted positions 262, 264. The firstmagnetic element 76 is secured to the first end 246 of the piston 244.The magnetic attraction between the first and second magnetic elements76, 78 is selected to hold the piston 244 in the extended position 262and prevent rotation of the contact arm 66, shaft 38, and valve 24 fromthe closed position 32 (counterclockwise in FIG. 37) of the valve 24until the torque exerted on the shaft 38 exceeds a preselectedmagnitude, at which time the magnetic catch will release and the pistonwill move towards the retracted position 264 allowing the valve 24 tomove to the open position 34. The previously discussed latch 270 may beprovided to latch the piston 244 in the retracted position 264 until thepiston 244 is manually returned to the extended position 262, aspreviously discussed. The passageway 333 is extended through the secondmagnetic element 78 so that the magnetic attraction between the firstand second magnetic elements 76, 78 may be balanced about thelongitudinal axis 260 of the piston 244 and the desired linearization ofthe forces acting on the piston 244 and magnetic catch 78 may beachieved. By doing so, the predictability and repeatability of the forcerequired to release the magnetic catch 74 and allow the valve 24 to movefrom the closed position 32 to the open position 34 are improved.

Referring to the example of FIG. 38, the linearizing means 240 isadapted for use with a tension pin 54. The tension pin 54 has a firstend 62 connected to the release support 72 and a second end 64 connectedto the second end 70 of the contact arm 66 so that the tension pinprevents rotation of the contact arm 66, shaft 38, and valve 24 from theclosed position 32 of the valve 24 (clockwise in FIG. 38) until thetorque exerted on the shaft 38 exceeds a preselected magnitude and thetension exerted on the pin 54 breaks the pin 54. A pivotable connector334 is pivotably connected to the second end 70 of the contact arm 66for securing the second end 64 of the tension pin 54 to the second end70 of the contact arm 66. The connector 334 pivots in about the sameplane or in a plane parallel to the rotational plane of the contact arm66 as the contact arm 66 attempts to rotate with the shaft 38 so thatthe longitudinal axis 294 of the pin 54 remains in alignment with atangent to the rotational arc of the second end 70 of the contact arm66. In the prototype assembly exemplified in FIG. 38, a hinged collarclamp 336 is connected to a free end 338 of pivotable connector 334. Thehinged collar clamp 336 secures the second end 64 of the tension pin 54to the pivotable connector 334. The hinged collar clamp 336 allows thesecond end 64 of the pin 54 to hinge or move in the same plane or in aplane parallel to the rotational plane of the contact arm 66 in order toallow the tensile forces exerted on the pin 54 by the rotating arm 66 toremain linear. The release support 72 includes a pin retainer block 340which is used to secure the first end 62 of the tension pin 54 to therelease support 72. The preferred pin retainer block 340 prevents motionof the tension pin 54 towards the contact arm 66 (until the burstpressure of the pin 54 is exceeded) but allows some lateral motion ofthe pin 54 so that the longitudinal axis 294 of the pin 62 may remainaligned with the tangent of the arc of rotation of the contact arm 66.The tension pin 54 should be made of a brittle material, such asgraphite or glass, which will not stretch when subjected to tensileforces but which will break or burst immediately when the designedrupture pressure of the tension pin 54 is exceeded. In the exampleembodiment of FIG. 38, the first and second ends 62, 64 of the pin 54are enlarged to facilitate their retention in the collar clamp 336 andretainer block 340.

Referring to the example of FIGS. 1 and 9, the housing 22 may be ofintegral, one piece construction, or assembled of components, e.g., theinlet 46 and outlet 48 may be separate components. The housing 22 mayalso be an integral part of the fluid pressure source, although thepreferred assembly 20 is an independent device. In the prototypeassembly 20, the inlet 46 and outlet 48 have a common, co-linear axis136, as exemplified in FIGS. 1 and 9, although the housing 22 may becurved or angled, as would be known to one skilled in the art in view ofthe disclosure contained herein.

The housing 22 and valve 24 should be shaped to facilitate at least 90degrees of rotation by the valve 24 (as exemplified in FIGS. 9 and 15)without interfering with the movement of the valve 24. In the prototypeassembly 20, the fluid passageway 50 is about circular when viewedaxially (as seen in FIGS. 3 and 8), and the valve 24 has a circumference92 of about the same shape as the fluid passageway 50. spacing rings(not illustrated) may be placed on either or both inlet 46 and outlet 48sides of the housing to provide additional axial clearance for the valve24 to rotate, as would be known to one skilled in the art in view ofthis disclosure.

Referring to the example of FIG. 8, as previously discussed, in the morepreferred embodiment of the assembly 20, the mounting means 26 or shaft38, includes first shaft end 348 and second shaft end 350 which arerotatably disposed in the housing 22, rotatably connect the valve 24 tothe housing 22, and define the rotational axis 28 of the valve 24. Therotational axis 28 is offset transversely from the diametrical axis 84of the valve 24 by the positioning of the first and second shaft ends348, 350 so that the fluid force in the inlet 46 of the housing 22 willcreate torque about the rotational axis 28, as previously discussed.Also, the connections of the shaft 38 and shaft ends 348, 350 to thevalve 24 are offset axially (axially along the flow axis 136 through thefluid passageway 50 as best seen in FIG. 9) from the seal planes 104,106 (FIG. 10) so that the connections of the shaft 38 and/or shaft ends348, 350 to the valve 24 do not physically obstruct or interfere withthe gap 94 and/or seal 96. This may be accomplished by relieving orcutting out the shaft ends 348, 350 where their connection to the valve24 coincides with the gap 94 and seal 96. Preferably, the first andsecond shaft ends 348, 350 do not extend into the fluid passageway 50.

The transverse offset of the rotational axis 28 from the diameter 84 ofthe valve 24 creates the fluid force imbalance and torque about therotational axis 28. The rotational axis 28 passes through the valve 24in a position which creates a larger first portion 124 of valve 24 and asmaller second portion 128 of valve 24. Since the fluid pressure exertsgreater force on the valve 24 on the larger first portion 124 of thevalve 24, the larger first portion 124 of the valve 24 is pushed towardsthe outlet 48 of the housing 22, thereby defining the direction ofrotation of the valve 24.

In the prototype assembly 20, a first offset bracket 352 is connectedbetween the first shaft end 348 and the valve 24 such that the joining354 of the first offset bracket 352 to the valve 24 is offset from therotational axis 28; and a second offset bracket 350 is connected betweenthe second shaft end 350 and the valve 24 such that the joining 358 ofthe second offset bracket 356 to the valve 24 is offset from therotational axis 28. In the prototype assembly 20, the first and secondoffset brackets 352, 356 extend through slots 360, 362 in the housing 22between the first and second shaft ends 348, 350 and fluid passageway50. The slots 360, 362 allow the first and second offset brackets 352,356 to transmit rotation of the valve 24 to the first and second shaftends 348, 350 and thereby to transmit torque from the shaft 38 to therelease means 40. The preferred offset brackets 352, 356 and diskbracket 364 are connected to the outlet face 90 of the valve 24 (ratherthan the inlet face 88) so that the outlet brackets 352, 356, slots 360,362, and shaft ends 348, 350 are not normally exposed to the fluids andpressures present in the housing inlet 46.

The disk bracket 364 is securely fastened or connected to the outletface 90 of the valve 24. The disk bracket 364 has opposite first andsecond ends 366, 368 which extend off of the valve 24. The offsetbrackets 352, 360 are welded to the opposite ends 366, 368 of the diskbracket 304 in the prototype assembly 20. As the valve 24 rotates fromthe closed position 32 to the open position 34, the first and secondends 366, 368 of the disk bracket 364 rotate in slots 360, 362 until theoutlet face 369 of the disk bracket at the disk bracket ends 366, 368contacts the ends of the slots 360, 362. The slots 360, 362 should besized to allow the valve 24 to rotate at least 90°, i.e., such that thediametrical plane of the valve 24 is about parallel with the flow axis136 of the housing inlet and outlet 46, 48. Also, the slots 360, 362 anddisk bracket 364 at the bracket ends 366, 368 should be constructed sothat when the valve 24 is in the closed position 32, the inlet face 370(FIG. 9) of the disk bracket 364 at the bracket ends 366, 368 contactsthe outlet face 372 of the housing 22 so that the valve 24 is securelyfixed and properly aligned in the closed position 32.

First and second bumpers 374, 376 are provided at the ends of slots 360,362 so that the outlet face 369 contacts the bumpers 374, 376 in theopen position 34 of the valve 24. The bumpers 374, 376 should be made ofa resilient polymer, plastic, or elastomer, such as Viton®, which willcompress sufficiently to allow the valve 24 to open a full 900 when apressure-relieving event occurs. The first and second bumpers 374, 376should also be strong enough to prevent the disk bracket 364 fromslamming into the housing 22 in a damaging manner, as will be known toone skilled in the art in view of the disclosure contained herein.

While presently preferred embodiments of the invention have beendescribed herein for the purpose of disclosure, numerous changes in theconstruction and arrangement of parts and the performance of steps willsuggest themselves to those skilled in the art in view of the disclosurecontained herein, which changes are encompassed within the spirit ofthis invention, as defined by the following claims.

What is claimed is:
 1. A linearizing mechanism, for converting thetorsional force of a rotatable shaft into a linear force on a housingadjacent the shaft, comprising:a release mechanism, located on thehousing, for preventing rotation of the shaft from a closed position toan open position when the torque exerted on the shaft is below aselected magnitude and for releasing the shaft in order to allowrotation of the shaft to the open position when the torque exerted onthe shaft exceeds a selected magnitude, the release mechanismcomprising:a contact arm having a first end connected to the shaft and asecond end spaced away from the rotational axis of the shaft; a releasesupport connected to the housing; and a pin connected to the releasesupport and obstructing rotation of the second end of the contact armand shaft until the torque exerted by the shaft exceeds a selectedmagnitude; and a pin seat, connected to the release support, forreceiving a first end of the pin; and a passageway, formed on therelease support, for slidably supporting a second end of the pin incontact with the second end of the contact arm, the pin seat andpassageway holding the pin with the longitudinal axis of the pin inalignment with a tangent to a rotational arc of the second end of thecontact arm so that the pin is subjected to a linear and compressiveforce as the shaft and second end of the contact arm rotate from theclosed position to the open position.
 2. Linearizing mechanism of claim1, comprising:a roller bearing connected to the second end of thecontact arm for rollingly and compressingly contacting the second end ofthe pin.
 3. Linearizing mechanism of claim 2, comprising:a piston,slidably mounted in the passageway on the release support between thepin and the contact arm and being slidable coaxially with thelongitudinal axis of the pin, the piston having a first end forcontacting the second end of the pin and a second end for contacting thesecond end of the contact arm, the piston being slidable between anextended position when the shaft is in the closed position and aretracted position when the shaft is in the open position. 4.Linearizing mechanism of claim 3, comprising:a roller bearing, connectedto one of the second end of the contact arm or the second end of thepiston, for rollingly and compressingly transferring the force of thesecond end of the contact arm through the piston to the pin. 5.Linearizing mechanism of claim 1:wherein the first and second ends ofthe pin are defined as being flat and perpendicular to the longitudinalaxis of the pin; and wherein the pin seat comprises:a pin seat sockethaving a longitudinal axis which coincides with the longitudinal axis ofthe pin when the pin is in the pin seat socket, the pin seat sockethaving a bottom surface which is flat and perpendicular to thelongitudinal axis of the pin seat socket.
 6. Linearizing mechanism ofclaim 1:wherein the first and second ends of the pin are flat andperpendicular to the longitudinal axis of the pin; and wherein the pinseat comprises:a pin seat socket for receiving the first end of the pinand having a longitudinal axis which coincides with the longitudinalaxis of the pin when the pin is in the pin seat socket, the pin seatsocket having a bottom surface which is flat and perpendicular to thelongitudinal axis of the pin seat socket; and wherein the first end ofthe piston comprises:a pin socket for receiving the second end of thepin and having a longitudinal axis which coincides with the longitudinalaxis of the pin when the pin is in the pin socket, the pin socket havinga bottom surface which is flat and perpendicular to the longitudinalaxis of the pin socket.
 7. Linearizing mechanism of claim 6:wherein theinside diameter of the pin seat socket is substantially equal to theoutside diameter of the first end of the pin so that the first end ofthe pin fits tightly into the pin seat socket; and wherein the insidediameter of the pin socket is substantially equal to the outsidediameter of the second end of the pin so that the second end of the pinfits tightly into the pin socket.
 8. Linear mechanism of claim 7:whereinthe depth of the pin seat socket is at least three times greater thanthe outside diameter of the first end of the pin; and wherein the depthof the pin socket is at least three times greater than the outsidediameter of the second end of the pin.
 9. Linearizing mechanism of claim3 in which the release support comprises:a latch having a first endconnected to the release support and a second end disposed between thesecond end of the piston and the pin when the shaft is in the closedposition and the piston is in the extended position, the latchcomprising:bias means for biasing the second end of the latch into aposition obstructing movement of the piston towards the extendedposition when the piston is in the retracted position.
 10. A linearizingmechanism, for converting the torsional force of a rotatable shaft intoa linear force on a housing adjacent the shaft, comprising:a releasemechanism, located on the housing, for preventing rotation of the shaftfrom a closed position to an open position when the torque exerted bythe shaft is below a selected magnitude and for releasing the shaft inorder to allow rotation of the shaft to the open position when thetorque exerted by the shaft exceeds a selected magnitude, the releasemechanism comprising:a contact arm having a first end connected to theshaft and a second end spaced away from the rotational axis of theshaft; a release support, connected to the housing for supporting thelinearizing mechanism; a shear pin; and a pin support, connected to therelease support, for receiving a first end of the pin and securelyholding the pin with the longitudinal axis of the pin perpendicular to atangent of a rotational arc of the second end of the contact arm; and inwhich the linearizing mechanism further comprises: a passageway, formedon the release support and extending between the pin and the contactarm; and a piston, slidably mounted in the passageway along a tangent ofthe rotational arc of the second end of the contact arm, the pistonhaving a first end for contacting the shear pin and a second end forcontacting the second end of the contact arm, the piston being slidablebetween an extended position when the shaft is in the closed positionand a retracted position when the shaft is in the open position, theshear pin holding the piston in the extended position and the shaft inthe closed position until the torque exerted on the shaft exceeds apreselected magnitude and the pin shears.
 11. A linearizing mechanism,for converting the torsional force of a rotatable shaft into a linearforce on a housing adjacent the shaft, comprising:a release mechanism,located on the housing, for preventing rotation of the shaft from aclosed position to an open position when the torque exerted by the shaftis below a selected magnitude and for releasing the shaft in order toallow rotation of the shaft to the open position when the torque exertedon the shaft exceeds a selected magnitude, the release mechanismcomprising:a contact arm having a first end connected to the shaft and asecond end spaced away from the rotational axis of the shaft; a releasesupport, connected to the housing, for supporting the linearizingmechanism; and a magnetic catch having a first magnetic element and asecond magnetic element located on the release support; and in which thelinearizing mechanism further comprises: a passageway formed on therelease support and extending between the second magnetic element andthe contact arm; and a piston, slidably mounted in the passageway alonga tangent of the rotational arc of the second end of the contact arm,the piston including a first magnetic element at a first end of thepiston and a second end for contacting the second end of the contactarm, the piston being slidable between an extended position when theshaft is in the closed position and a retracted position when the shaftis in the open position, the magnetic attraction between the first andsecond magnetic elements being selected to hold the piston in theextended position and prevent rotation of the contact arm and shaft fromthe closed position until the torque exerted on the shaft exceeds apreselected magnitude.
 12. A linearizing mechanism, for converting thetorsional force of a rotatable shaft into a linear force on a housingadjacent the shaft, comprising:a release mechanism, located on thehousing, for preventing rotation of the shaft from a closed position toan open position when the torque exerted on the shaft is below aselected magnitude and for releasing the shaft in order to allowrotation of the shaft to the open position when the torque exerted onthe shaft exceeds a selected magnitude, the release mechanismcomprising:a contact arm having a first end connected to the shaft and asecond end spaced away from the rotational axis of the shaft; a releasesupport connected to the housing; and a tension pin having a first endconnected to the release support and a second end connected to thesecond end of the contact arm so that the pin prevents rotation of thecontact arm and shaft from the closed position until the torque exertedon the shaft exceeds a preselected magnitude, the tension pin having alongitudinal axis extending through the first and second ends; thelinearizing mechanism further comprising: a pivotable connector,pivotably connected to the second end of the contact arm for securingthe second end of the tension pin to the second end of the contact arm,the connector pivoting as the contact arm rotates with the shaft fromthe closed position to the open position of the valve so that thelongitudinal axis of the pin remains in alignment with a tangent to arotational arc of the second end of the contact arm.
 13. Mechanism ofclaim 12:wherein the tension pin is further defined as being made of abrittle material which will not stretch when subjected to tensileforces.